Preheat the oven to 450 degrees.
Bring a pot of salted water to a boil. Add in as many potatoes as you wish to make and cook them until they are fork-tender.
Drizzle a sheet pan with olive oil. Place tender potatoes on the sheet pan, leaving plenty of room between each potato.
With a potato masher, gently press down each potato until it slightly mashes, then push the excess out of the masher back on top of the potatoes. Rotate the potato masher 90 degrees and mash again, pushing out the excess. Drizzle the tops of each crushed potato generously with more olive oil.
Sprinkle potatoes with kosher salt, fresh ground black pepper and fresh chopped rosemary (or chives or thyme or whatever herb you have available.) Add grated Parmesan.
Bake in a 450 degree oven for 20-25 minutes until golden brown and sizzling.